HFG senior nutritionist Rose Carr investigates the role of sugar in our diet.
I’ve heard that sugar is ‘toxic’ and that sugar is the real reason for the obesity epidemic. Is that true?
There is no evidence that sugar itself is toxic. We do know, however, that consuming an excessive amount of sugar-laden foods can make us obese and have a detrimental effect on our health.
Labelling sugar as toxic seems to be the latest way to scare us into doing something about the nutrient-poor, energy-dense diets many people consume. As such, the ‘toxic sugar’ label may have more to do with psychology than biochemistry or physiology. While we would all love to find a magical solution to the obesity problem, to say that sugar is the sole cause of obesity is too simplistic. Sugar is one of a number of factors implicated in the rise of obesity.
Will cutting out sugar lead to drastic weight-loss?
The answer to this depends very much on how many sugary foods you are eating! If you drink lots of sugar-sweetened soft drinks, regularly eat generous amounts of cake, biscuits, confectionery and sugary cereal, and pour sugar into your tea and coffee, cutting out these things will result in weight-loss. If, however, you only consume these foods and drinks occasionally, and in moderate amounts, any noticeable weight-loss may be a long time coming. Of course this also assumes that if you do cut out sugary foods, you won’t replace them with just as much energy from another source.
Is there a difference between table sugar and sugar in fruit? Or is it all bad?
Sucrose, known as table sugar, is made up of the sugars glucose and fructose joined together. Fruits contain the sugars fructose, glucose and sucrose in varying amounts. The main sugar in milk is lactose.
Fructose from fruit is metabolised in the same way as any other fructose. The difference between fruit and other sources of fructose is that fruit contains vitamins, minerals, fibre and a huge range of phytonutrients which also benefit our health. There are many proven health benefits of including fruit in our diets.
What’s the theory behind ‘toxic sugar’?
The toxic sugar proponents tell us that because fructose is metabolised differently than glucose, it is more likely to be transformed into body fat. The focus is on fructose from table sugar or high fructose corn syrup (HFCS), which is the most commonly used sweetener in manufactured foods in North America (it ishardly used at all in New Zealand).
Continued high consumption of fructose has been tested on laboratory rats and found to cause insulin resistance, obesity, type 2 diabetes and high blood pressure. In people, it’s known that high fructose consumption will increase blood triglycerides. More recently, it’s been shown that when high fructose consumption is part of a high-kilojoule diet it can also increase insulin resistance. The catch is that this insulin resistance cannot be attributed to fructose alone: insulin resistance can also be caused by a high-energy diet that is high in fat or high in glucose. The excess kilojoules seem to have more impact on insulin resistance than the source of the excess kilojoules — which suggests it is still a very good idea to balance the energy (kilojoules) we consume from all foods with the energy we use.
Should I cut out the sugar in my kids’ diets?
It’s a good idea for all of us, young and old, to limit sugary foods but that doesn’t mean we need to forgo them entirely. It’s OK for food to be a pleasure and not just a necessity. The issue we have today is that high-energy foods, including foods high in sugar, are so readily available to us it can be harder tokeep the balance right. And while it’s natural for us to like sweet foods, if everything we eat is highly sweetened when we are young, we may carry on eating everything highly sweetened throughout life — which is bound to mean we are consuming excess kilojoules.
Differentiating between everyday foods and occasional treat foods is important in developing lifetime food habits. Learning to eat mindfully with all foods, and especially with treat foods, can help us and our children get the dietary balance right. Get kids to eat their treats consciously, while sitting down, ratherthan mindlessly eating while doing other activities. Other common traps for parents include kids’ breakfast cereals with 30-50 per cent sugar (often posing as healthy food), the temptation to use biscuits and confectionery as a bribe for good behaviours, and pester-power! It is also really important to encouragechildren to drink plain water as the drink of choice, to avoid drinking sugar-sweetened drinks regularly.
Is it possible to be addicted to sugary foods?
This question is currently receiving a lot scientific attention. It seems there is a level of disagreement in the scientific community on whether or not sugary foods can be classed as addictive.
In medical terms, an addictive substance must: induce a pleasant state; cause long-term chemical changes in the brain; cause adaptive changes in the brain leading to tolerance, physical dependence and uncontrollable cravings; and cause dependence such that abstinence creates severe physical and mental reactions.
While some would argue sugar cannot cause physical dependence in the same way as heroin, others are studying the similarities of brain reactions in highly palatable foods compared to drugs of abuse.
In the meantime, if you feel you or someone you know does have a physical dependence on a sugary (or other) food, there is some evidence that treatment similar to that used in other types of addiction may help.
How much sugar (added or otherwise) is okay?
In New Zealand, we don’t have specific guidelines for the amount of sugars we ought to consume and internationally there is no agreed optimal upper intake for sugars, although people with metabolic syndrome or who are overweight are advised to limit sugar consumption. If we follow the general guidelines for healthy eating, however, we will naturally be limiting our sugar intake as we fill up on nutrient-rich foods. We will be eating plenty of vegetables and fruit; favouring wholegrain cereals; including lean meats, fish, eggs, nuts, seeds and legumes; choosing low-fat milk and dairy products; and drinking water and unsweetened water-based drinks as our main fluids.
When analysing foods or diets it is not usually possible to distinguish between added sugars and naturally occurring sugars, and the body doesn’t treat them any differently either. On nutrition information panels on food products you will see the amount of sugars listed and this will include both naturally occurring andadded sugars, so check ingredients lists to find added sugar.
Don’t drink all your sugar
It can be easy to drink a lot of sugar without realising it. Consumption of sugar-sweetened drinks such as soft drinks, fruit drinks, energy drinks and vitamin waters has grown around the world in the past few decades. These drinks are the main source of added sugars in the US and there have been numerous studiesinvestigating their effects. Regular consumption of sugar-sweetened drinks is linked with weight gain and the risk of becoming overweight and obese. There is also growing evidence that higher consumption of sugar-sweetened drinks is associated with the development of metabolic syndrome and type 2 diabetes.